44 Magnum bullet weights, I'm stumped

[The Dar]

I cast some Lee TL430-240-SWC bullets and some Lee 429-240-2R bullets recently. The bullets were cast from the same pot of alloy on the same day. I powder coated and sized them tonight, and decided to weigh a few of them. Both bullets should weigh near 240 grains. The TL430-240 SWC's came in at 239 grains. The 429-240-2R's came in at 259 grains. Could Lee have marked the mold wrong? Or perhaps cut the mold too deep? I'm stumped, any thoughts?

[Larry Gibson]

Might weigh some before powder coating. Also the alloy used can give a marked difference in bullet weight. Moulds are cut for a certain ally for a specific weight +/-. If you use an alloy with a higher % of lead the bullets will be heavier. If your alloy has a lower % of lead then your bullets will be lighter.

[JonB_in_Glencoe]

Lee molds can vary, especially the pre-2013 two cavity molds. Lee changed how they cut their 2 cav molds in 2013 and I haven't seen or heard of much "out of spec" since then. But even so, that is quite a bit "out of spec". I did this comparison with some 30 cal molds I bought in 2010 and '11.
http://castboolits.gunloads.com/showthread.php?189534-Lee-30-cal-2-cav-molds-not-necessarily-as-advertised&highlight=

Is your mold, that is dropping a 259gr boolit over 5 years old?
If so, it's probably what Lee cut it to.
BUT, if it's a new mold, I suspect there is something that is keeping you from fully closing the mold. Like a tight fitting alignment pin or some metal Burr or a bit of alloy on the mold face.

[reloader28]

Almost every mold from every maker I have cast heavier than specified. The manufacturers always use a special blend alloy that nobody else uses. I seem to gain about 4 actual grains for every 100 grains of advertised bullet weight. Dont matter if its lee, lyman ,rcbs and I use straight COWW

My NOE and ACCURATE molds are spot on but you punch in what alloy your using when you order

[stubert]

Ditto what Larry said, also you might want to measure the diameter as cast.

[white eagle]

don't worry to much about weight see how they shoot for ya

[1bluehorse]

Lyman molds get their weight number using Lyman #2 alloy. I would just be guessing but RCBS probably uses #2 also. Like said above, custom mold makers will cut their molds to drop to weight using what ever alloy you specify. I have no idea what specs Lee uses for their molds, but wouldn't surprise me if they use the same as Lyman.

[mdi]

Besides alloy, some other things can affect bullet weight; mold temp., melt temp., and pour method. I've experienced weight variations, while slight, by varying these factors...

[44Blam]

I try to get my alloy as close to #2 as possible with lead + lino + tin. I noticed that my boolits tend to cast slightly lighter than the mold weight. So a 405 grn turns out to be around 402 or so and my .430 (44 mag) 240s tend to weigh in around 238-239. But sometimes when the mold is (not sure warm/cold?) I get a few outliers that are 5 or so grains +/- and I notice when resizing, some are a little fatter (and heavier). All the ones that don't size get culled, so I only end up with the heavier / normal ones...

[The Dar]

Sorry I haven't gotten back to y'all sooner, been busy. I use a hot plate to heat my molds. I normally get good bullets from the first cast. I don't start casting till the alloy in the pot hits 700 degrees. I maintain the heat between 700 and 720 degrees (digital thermometer). When one mold got hot I pulled the other mold off the hot plate and used it. I kept alternating between molds using the same alloy and technique. Both molds are sold as 240 grains, but I don't understand the 20 grain difference. I'll cast the same two molds again and weigh the bullets before PC. I will shoot both of the bullets. I haven't found a bullet yet that my 6" Model 29 doesn't like.

[Walter Laich]

If all the bullets from one mold weigh about the same and same with the other mold don't worry

if you're getting a great spread from the same mold with same alloy then something isn't correct